Add MemberGroup descriptions (System.Something)

[gewarren]

Contributes to #12626.

[Copilot]

Pull request overview

This PR addresses #12626 by adding missing <MemberGroup> entries (with <summary> text) so overload groups have descriptions in the generated API reference.

Changes:

• Added <MemberGroup> summary blocks for many overloaded methods/constructors across System.* APIs.
• Improved overload-list discoverability by ensuring key overload groups (async I/O, LINQ, hashing, compression, etc.) have top-level descriptions.
• Added constructor (.ctor) group descriptions for multiple types where overload grouping exists.

Reviewed changes

Copilot reviewed 93 out of 93 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
xml/System.Xml/XmlDocumentXPathExtensions.xml	Add MemberGroup summaries for XPath extension overload groups.
xml/System.Xml.Serialization/CodeIdentifiers.xml	Add MemberGroup summary for constructors.
xml/System.Xml.Linq/XElement.xml	Add MemberGroup summaries for async and conversion operator overload groups.
xml/System.Xml.Linq/XDocument.xml	Add MemberGroup summaries for async load/save overload groups.
xml/System.Xml.Linq/XAttribute.xml	Add MemberGroup summary for conversion operator overload group.
xml/System.ServiceProcess/ServiceController.xml	Add MemberGroup summaries for Dispose/Stop overload groups.
xml/System.ServiceProcess/ServiceBase.xml	Add MemberGroup summary for RequestAdditionalTime overload group.
xml/System.Resources.Extensions/PreserializedResourceWriter.xml	Add MemberGroup summaries for ctor and AddResource overload group.
xml/System.Resources.Extensions/DeserializingResourceReader.xml	Add MemberGroup summary for constructors.
xml/System.Linq/Queryable.xml	Add MemberGroup summaries for many LINQ overload groups.
xml/System.Linq/ParallelEnumerable.xml	Add MemberGroup summaries for PLINQ overload groups.
xml/System.Linq/IOrderedAsyncEnumerable`1.xml	Add MemberGroup summary for CreateOrderedAsyncEnumerable overload group.
xml/System.Linq/ImmutableArrayExtensions.xml	Add MemberGroup summaries for multiple ImmutableArray extension overload groups.
xml/System.Linq/Enumerable.xml	Add MemberGroup summaries for many LINQ overload groups.
xml/System.Linq.Expressions/Expression`1.xml	Add MemberGroup summary for Compile overload group.
xml/System.Linq.Expressions/Expression.xml	Add MemberGroup summary for Lambda overload group.
xml/System.IO/UnmanagedMemoryStream.xml	Add MemberGroup summaries for Read/Write async/sync overload groups.
xml/System.IO/TextWriter.xml	Add MemberGroup summary for FlushAsync overload group.
xml/System.IO/TextReader.xml	Add MemberGroup summaries for async read overload groups.
xml/System.IO/StringWriter.xml	Add MemberGroup summary for WriteLine overload group.
xml/System.IO/StringReader.xml	Add MemberGroup summaries for async read overload groups.
xml/System.IO/StreamWriter.xml	Add MemberGroup summaries for FlushAsync/WriteLine overload groups.
xml/System.IO/StreamReader.xml	Add MemberGroup summaries for async read overload groups.
xml/System.IO/Stream.xml	Add MemberGroup summaries for Read/ReadExactly/Write overload groups.
xml/System.IO/Path.xml	Add MemberGroup summaries for span-based path API overload groups.
xml/System.IO/MemoryStream.xml	Add MemberGroup summaries for Read/Write async/sync overload groups.
xml/System.IO/FileSystemWatcher.xml	Add MemberGroup summary for Dispose overload group.
xml/System.IO/FileSystemAclExtensions.xml	Add MemberGroup summaries for ACL extension overload groups.
xml/System.IO/FileStream.xml	Add MemberGroup summaries for Read/Write async/sync overload groups.
xml/System.IO/FileInfo.xml	Add MemberGroup summary for MoveTo overload group.
xml/System.IO/File.xml	Add MemberGroup summaries for many File API overload groups.
xml/System.IO/BufferedStream.xml	Add MemberGroup summaries for Read/Write async/sync overload groups.
xml/System.IO.Pipes/PipeStream.xml	Add MemberGroup summaries for Read/Write async/sync overload groups.
xml/System.IO.Pipelines/StreamPipeReaderOptions.xml	Add MemberGroup summary for constructors.
xml/System.IO.Pipelines/PipeReader.xml	Add MemberGroup summaries for CopyToAsync/Create overload groups.
xml/System.IO.Pipelines/Pipe.xml	Add MemberGroup summary for constructors.
xml/System.IO.IsolatedStorage/IsolatedStorageFileStream.xml	Add MemberGroup summaries for Read/Write async/sync overload groups.
xml/System.IO.Hashing/XxHash64.xml	Add MemberGroup summaries for ctor/hash overload groups.
xml/System.IO.Hashing/XxHash32.xml	Add MemberGroup summaries for ctor/hash overload groups.
xml/System.IO.Hashing/XxHash3.xml	Add MemberGroup summaries for ctor/hash overload groups.
xml/System.IO.Hashing/XxHash128.xml	Add MemberGroup summaries for ctor/hash overload groups.
xml/System.IO.Hashing/NonCryptographicHashAlgorithm.xml	Add MemberGroup summaries for Append/Get*Hash overload groups.
xml/System.IO.Hashing/Crc64.xml	Add MemberGroup summaries for ctor/hash overload groups.
xml/System.IO.Hashing/Crc32.xml	Add MemberGroup summaries for ctor/hash overload groups.
xml/System.IO.Enumeration/FileSystemEnumerator`1.xml	Add MemberGroup summary for Dispose overload group.
xml/System.IO.Compression/ZstandardStream.xml	Add MemberGroup summary for constructors.
xml/System.IO.Compression/ZstandardEncoder.xml	Add MemberGroup summary for constructors.
xml/System.IO.Compression/ZstandardDecoder.xml	Add MemberGroup summary for constructors.
xml/System.IO.Compression/ZLibStream.xml	Add MemberGroup summaries for ctor/read/write overload groups.
xml/System.IO.Compression/ZLibEncoder.xml	Add MemberGroup summary for constructors.
xml/System.IO.Compression/ZipFileExtensions.xml	Add MemberGroup summaries for zip extension overload groups.
xml/System.IO.Compression/ZipFile.xml	Add MemberGroup summaries for async zip operations overload groups.
xml/System.IO.Compression/ZipArchiveEntry.xml	Add MemberGroup summaries for Open/OpenAsync overload groups.
xml/System.IO.Compression/GZipStream.xml	Add MemberGroup summaries for read/write overload groups.
xml/System.IO.Compression/GZipEncoder.xml	Add MemberGroup summary for constructors.
xml/System.IO.Compression/DeflateStream.xml	Add MemberGroup summaries for read/write overload groups.
xml/System.IO.Compression/DeflateEncoder.xml	Add MemberGroup summary for constructors.
xml/System.IO.Compression/BrotliStream.xml	Add MemberGroup summaries for ctor/read/write overload groups.
xml/System.IO.Compression/BrotliEncoder.xml	Add MemberGroup summary for TryCompress overload group.
xml/System.Globalization/StringInfo.xml	Add MemberGroup summary for GetNextTextElementLength overload group.
xml/System.Globalization/ISOWeek.xml	Add MemberGroup summaries for ISO week helper overload groups.
xml/System.Formats.Tar/V7TarEntry.xml	Add MemberGroup summary for constructors.
xml/System.Formats.Tar/UstarTarEntry.xml	Add MemberGroup summary for constructors.
xml/System.Formats.Tar/TarWriter.xml	Add MemberGroup summaries for ctor/write overload groups.
xml/System.Formats.Tar/TarFile.xml	Add MemberGroup summaries for create/extract overload groups.
xml/System.Formats.Tar/PaxTarEntry.xml	Add MemberGroup summary for constructors.
xml/System.Formats.Tar/GnuTarEntry.xml	Add MemberGroup summary for constructors.
xml/System.Formats.Nrbf/NrbfDecoder.xml	Add MemberGroup summaries for Decode and StartsWithPayloadHeader overload groups.
xml/System.Formats.Cbor/CborWriter.xml	Add MemberGroup summaries for ctor/encode/write overload groups.
xml/System.Formats.Cbor/CborContentException.xml	Add MemberGroup summary for constructors.
xml/System.Formats.Asn1/ValueAsnReader.xml	Add MemberGroup summaries for ReadSetOf/ReadUtcTime overload groups.
xml/System.Formats.Asn1/AsnWriter.xml	Add MemberGroup summaries for ctor/encode/write overload groups.
xml/System.Formats.Asn1/AsnReader.xml	Add MemberGroup summaries for ReadSetOf/ReadUtcTime overload groups.
xml/System.Formats.Asn1/AsnContentException.xml	Add MemberGroup summary for constructors.
xml/System.Formats.Asn1/Asn1Tag.xml	Add MemberGroup summaries for ctor/Equals overload groups.
xml/System.Buffers/StandardFormat.xml	Add MemberGroup summary for Parse overload group.
xml/System.Buffers/SequenceReaderExtensions.xml	Add MemberGroup summaries for endian read overload groups.
xml/System.Buffers/SequenceReader`1.xml	Add MemberGroup summaries for multiple reader helper overload groups.
xml/System.Buffers/SearchValues.xml	Add MemberGroup summary for Create overload group.
xml/System.Buffers/ReadOnlySequence`1.xml	Add MemberGroup summaries for ctor/GetPosition/Slice overload groups.
xml/System.Buffers/NRange.xml	Add MemberGroup summaries for ctor/Equals overload groups.
xml/System.Buffers/NIndex.xml	Add MemberGroup summaries for ctor/Equals/op_Implicit overload groups.
xml/System.Buffers/MemoryPool`1.xml	Add MemberGroup summary for Dispose overload group.
xml/System.Buffers/MemoryManager`1.xml	Add MemberGroup summary for CreateMemory overload group.
xml/System.Buffers/ArrayPool`1.xml	Add MemberGroup summary for Create overload group.
xml/System.Buffers/ArrayBufferWriter`1.xml	Add MemberGroup summary for constructors.
xml/System.Buffers.Text/Utf8Parser.xml	Add MemberGroup summary for TryParse overload group.
xml/System.Buffers.Text/Utf8Formatter.xml	Add MemberGroup summary for TryFormat overload group.
xml/System.Buffers.Text/Base64Url.xml	Add MemberGroup summaries for Base64Url encode/decode/validate overload groups.
xml/System.Buffers.Text/Base64.xml	Add MemberGroup summaries for Base64 encode/decode/validate overload groups.
xml/System.Buffers.Binary/BinaryPrimitives.xml	Add MemberGroup summary for ReverseEndianness overload group.